What do you think? Leave a respectful comment.

Climate Change From Different Perspectives

Anything dealing with climate change is bound to provoke an argument. And our story on Berkeley physicist Richard Muller’s recent conversion to a believer in man-made global warming, which he made in an op-ed in the New York Times, certainly stirred the pot. In addition to preparing a video story on the PBS NewsHour, I had written a blog that included extended remarks from Anthony Watts, a well-known blogger and prominent voice in the skeptic community. Watts — a former California TV weatherman who runs a company that provides weather data to TV stations — says he doesn’t completely discount global warming, but he says that much of the data recording temperatures are flawed because the stations are in areas like urban settings which retain heat and therefore read too high.

The idea of the online post — in part — was to let the audience hear more about the views of a prominent voice from the community of skeptics. In the past, we have on occasion provided a more expansive view from the overwhelming majority of climate scientists who say climate change is real, an ever-growing problem and one that is getting significantly worse because of our own contribution to greenhouse gases. (In fact, my colleague Hari Sreenivasan posted links to some of that prior reporting earlier today.) We thought the online post with Watts would provide a chance for viewers to hear more about the skeptical perspective than we have done recently.

That said — and as many of you wrote us to complain — we should have not ONLY posted additional comments from Watts’ perspective. So we have more interviews and responses from the scientific community about climate change. Let’s start on the question of whether temperature data is flawed. That was raised by Watts, and his views on that are being heavily criticized on the web today.

The National Oceanic and Atmospheric Administration wrote a response to us and stands by its record on temperature data. Here is what NOAA sent:

The American public can be confident in NOAA’s long-standing surface temperature record, one of the world’s most comprehensive, accurate and trusted data sets. This record has been constructed through many innovative methods to test the robustness of the climate data record developed and made openly available for all to inspect by NOAA’s National Climatic Data Center. Numerous peer-reviewed studies conclusively show that U.S. temperatures have risen and continue to rise with recent widespread record-setting temperatures in the USA. There is no doubt that NOAA’s temperature record is scientifically sound and reliable. To ensure accuracy of the record, scientists use peer-reviewed methods to account for all potential inaccuracies in the temperature readings such as changes in station location, instrumentation and replacement and urban heat effects.

Specifically, NOAA’s National Climatic Data Center published a scientific peer-reviewed paper (Menne, et al., 2010) that compared trends from stations that were considered well-sited and stations that received lower ratings on siting conditions, which found that the U.S. average temperature trend is not inflated by poor station siting. A subsequent research study led by university and private sector scientists reached the same conclusion (Fall et al. 2011). Additionally, the Department of Commerce Inspector General reviewed the US Historical Climatology Network dataset in July 2010 and concluded that “the respondents to our inquiries about the use of and adjustments to the USHCN data generally expressed confidence in the [USHCN] Version 2 dataset.”

Looking ahead to the next century, NOAA has implemented the U.S. Climate Reference Network (USCRN) – with 114 stations across the contiguous United States located in pristine, well-sited areas. Comparing several years of trends from the well-sited USCRN stations with USHCN shows that the temperature trends closely correspond – again validating the accuracy of the USHCN U.S. temperature record.

NOAA also provides this link for those who want more information.

There are plenty of other links where you can find data and information about this question of temperature measurements. One of note that we are including here is the website, skepticalscience.com, which examines and pushes back on the critique from the skeptics’ community.

One point that we tried to make in the broadcast piece was that Richard Muller, in fact, had his own doubts in the past on temperature readings with some issues that were similar to Watts’ criticisms. But he and his daughter, mathematician Elizabeth Muller, told us they looked closely at climate data and now clearly believe that human-induced climate change is happening. Here’s more of what they told us:

Read the transcript:

SPENCER MICHELS: But it was more than just I’m not sure of your data and how you analyzed it, it was you really didn’t quite believe that the earth was warming. Wasn’t that part of it?

RICHARD MULLER: Right, the, the, I did not know that the earth was warming because the evidence that indicated that was uh, was corrupt in a way that I could not convince myself as a scientist looking at the same data that had been handled in a way that, that took care of that.

SPENCER MICHELS: Now you have done some of the research on, no their research, some data studies. You found that they essentially were right though, right?

RICHARD MULLER: What we found was actually even stronger than that. We got the same data that they used and then did a completely independent analysis. About 9 months ago we concluded that the global warming they had reported was accurate. What that meant was that the things that we had looked at, the things that had bothered me, they had undoubtedly handled internally in such a way that, that it worked out, worked out fine. So they had actually done a good job it’s just that I couldn’t tell that they had done a good job. So yes, global warming was real.

ELIZABETH MULLER: We were skeptical because of these issues and we felt that anybody who was aware of these issues should also have been skeptical, because these were serious concerns um, with the, the record that needed to be addressed.

SPENCER MICHELS: Was there any political component in any of your doubts?

ELIZABETH MULLER: No, I think we were trying to keep an open mind from the beginning and we went into the study saying we honestly didn’t know what we were going to find. We didn’t know if there was going to be, we were going to find that there was less global warming. We didn’t know if we were going to find that there was more global warming. We were trying to keep a very open mind from the beginning.

SPENCER MICHELS: So you did a statistical analysis of, of the data that was out there, right?

ELIZABETH MULLER: That’s right. So we used all of the data, or essentially all of the data five times more than any other group had, had done, um, and we also looked at these specific issues, such as the station quality issue, the urban heat island effect, um, and uh, some of the other issues that had been raised by skeptics, and after having done all of that, we determined that the previous um, the previous studies on global warming had been about right. Um, there was global warming at about 1 degree Celsius in the past 50 years um, and that was a big surprise to us. I think the last thing we expected was to confirm um, previous studies. Um, but I think it shows that they were actually a lot more careful than we had given them credit for.

In our broadcast piece, we also included an interview with William Collins, a senior scientist at the Lawrence Berkeley Laboratory and head of the climate science department. He has been a leading scientist on global warming, and has written and spoken extensively about it. These are excerpts from an interview done by Chris Bauer of KQED’s Quest where Collins explains, among other things, the role of mankind in global warming.

Read the transcript:

WILLIAM COLLINS: So one, one question that I think that occurs to many people is how do we know that global warming is due to mankind? ‘Cos after all, if you go to the Grand Canyon, you see a history of climate for the last 600 million years right there on the canyon walls in front of you. So it’s obvious the Earth’s climate can change, and it can change for perfectly natural reasons. So we’ve been looking for fingerprints of man’s influence on climate sort of in some sense, a smoking gun, that would prove that it’s man that’s causing the change. And we’ve actually found those fingerprints in the climate system. Some of them have to do with how the temperature of the surface and the atmosphere are changing together. It turns out that that’s a very strong fingerprint of manmade climate change. You can’t get that, that single that we’re seeing from volcanoes. You can’t get that signal from the sun. And those are two of the, really, the primary natural causes for climate change. The only way that we know of to get the atmosphere’s temperature to change in the way that it’s changed since the early 20th century is to add greenhouse gases. So that’s a fairly strong hint. We also know from very good evidence that man is responsible for the increase in greenhouse gases. We can show that from basic laboratory chemistry. And that, that fact is really not in much dispute. So there’s several signatures like the temperature that implicate man. You can’t get climate to change in the way that it’s changing, for example, if we have fewer volcanoes today than we had in the middle of the 20th century. Just not possible.

Abrupt climate change has become an important issue for us now. It’s this joker in the deck that we discussed, where climate may respond quickly and change in a way that’s almost irreversible. So for example, if a major piece of Antarctica were to break off, we would regard that as a form of abrupt climate change. And once the ice breaks off of Antarctica, it will contribute to sea level rise. The melting of glaciers on land, it’s a slower process. That’s a form of irreversible climate change. At least in our lifetimes. Once those glaciers go away we won’t see them come back for thousands of years. So we’re increasingly concerned about changes in the climate system where large parts of the Earth may change. All at once. Quite quickly. And we may not see it coming until it happens.

One question I frequently hear is what does it matter that people are causing climate change? Well, the cause really does matter, because the cause and the solution for climate change are closely linked. If the sun is responsible for the change that we’re seeing now, then we need to figure out how to make our cities brighter so they’ll reflect more sunlight back to space. If volcanoes are responsible for climate change, then there’s another solution we need to pursue. The fact that people are causing climate change means that we have to change how we produce energy. It’s really that simple.

Finally, one other point to note.

In our broadcast piece, we said that “…Judith Curry, professor of earth sciences at Georgia Tech, who suspects natural variability accounts for climate change — not human-produced CO2 — said Muller’s analysis is “way oversimplistic and not at all convincing…”

Curry wrote to us earlier today to say that she believes we didn’t characterize her position fully and said she was “appalled” with what we said.

Here’s what Curry told us:

It is correct that I found Muller’s analysis “way oversimplistic and not at all convincing”, but the statement implies that that I don’t think human-produced CO2 accounts for any of the climate change we have been seeing. This is absolutely incorrect. For my views on climate change, see my blog Climate Etc. http://judithcurry.com. In my most recent posts on the Arctic sea ice decline, I estimated that about half the decline could be attributed to human induced CO2, which is in line with the latest analyses from the CMIP5 climate models.

In retrospect, we should have said that Curry suspects natural variability accounts for some amount of climate change, but she also believes human-induced CO2 plays some role in what has been happening to the planet.

For those who want to look more deeply into the dialogue and data online, there is no shortage of resources. And we don’t expect this to be the last word in our own coverage. But we hope we’ve provided a bit more perspective to yesterday’s post and the broadcast piece.

The Latest